LCDs are widely used in various modern electronics, such as notebook computers, personal digital assistants, and video cameras, for example. In general, an LCD includes a voltage generating circuit to provide a common voltage for the LCD. Precise common voltage adjustments may be made to the LCD to improve a display quality of the LCD.
FIG. 5 shows one embodiment of a conventional common voltage generating circuit 20 used in an LCD. In the embodiment of FIG. 5, the common voltage generating circuit 20 includes a controller 210, a plurality of resistors 220, and a plurality of switches 230. The resistors 220 are electrically coupled in series, and cooperatively constitute a resistor-string to form a voltage divider. A voltage output 231 is configured to provide a common voltage for a liquid crystal panel (not shown) of the LCD.
Typically, the voltage generating circuit 20 is large in size and complicated due to the numerous resistors 220. Additionally, the voltage generating circuit 20 may not output precise common voltage adjustments to the LCD due to the voltage generating circuit 20 having a finite number of resistors 220. The finite number of resistors 220 limits a number of possible voltage outputs for the voltage output 231. Accordingly, when a common voltage, with low precision adjustments, is applied to the LCD, a display quality of the LCD may be perceived as being of a low quality.
It is, therefore, desired to provide a common voltage generating circuit and an LCD using the common voltage generating circuit which can overcome the above-described deficiencies.